Water pressure sensors are used in a wide variety of applications, including monitoring the pressure of water in a local water supply system. One type of pressure sensor apparatus includes a housing that forms a channel with a water inlet at one end of the channel and with a pressure sensor at the far end of the channel. Water can flow through the channel towards and away from the pressure sensor at the far end of the channel.
Water undergoes about a 10% increase in volume when it freezes, and the water can exert an expansion force on the order of magnitude of 110,000 pounds per square inch when it freezes. The expansion force of water in the channel of a pressure sensor apparatus could damage the relatively fragile pressure sensor at the far end of the channel. There is a need for a design of a water pressure sensor apparatus that avoids such damage.
U.S. Pat. No. 8,051,719 describes a pressure sensor device that avoids damage by including a compressible element in the channel that leads to the pressure sensor, or by including a compressible element in a volume that connects to the channel far end. A design that avoided damage without requiring room for an expandable element and without requiring an expandable element itself, would be of value.